Many new aircraft engines, including both engines currently in development and engines recently certified for flight use, employ electronic engine control systems. As well, older aircraft, designed before electronic control systems were common, are sometimes retrofitted with such systems. Among other advantages, electronic engine control systems can help to reduce pilot workload, provide simpler and more efficient interfaces with modem cockpit control systems, provide improved protection for engines against extreme operating conditions, and enhance prognostic and diagnostic capabilities.
An important parameter to be controlled by an electronic engine controller in a turboprop or turboshaft engine is engine output power (or output torque). Such power is most often controlled through control of the rate of fuel flow provided to the engine.
For measuring and reporting current engine power output, prior art engine controllers have typically employed mechanical transducers, such as phase-shift torque meters. Such mechanical transducers, however, require space and add weight to an engine; the addition of either volume or weight to engines is typically undesirable, particularly in aerospace applications. In a turboprop or turboshaft engine, for example, the use of such transducers can require modification of the reduction gearbox (RGB) and associated components.